Redistribution of runoff is a fundamental ecohydrological processes in semiarid woodlands. Runoff is often generated from intercanopy patches that separate the canopy patches of woody plants, particularly from locations with bare soil, and subsequently captured by vegetation patches, where the concentration of resources can be ecologically significant. Although redistribution by erosion also occurs, less well documented is the extent to which biogeochemical patterns such as total C and total N are affected, particularly in rapidly eroding hillslopes where redistribution might be greatest. We measured total soil C and total soil N at two hillslope positions (upslope and downslope) for interill areas including two patch types (canopies of woody plants and intercanopies separating them) and for rill areas in a rapidly eroding semiarid piñon-juniper woodland in northern New Mexico, USA.
Results/Conclusions
Downslope interill locations of either patch type had greater concentrations of total C and total N than corresponding upslope locations of the same patch type, with canopy patches having greater concentrations than intercanopy patches as is commonly observed. Conversely, downslope rill locations were depleted in total C and total N relative to upslope rill locations by about 15% in both cases. These results, in concert with related studies, suggest total C and total N are being concentrated via runoff downslope from intercanopy locations, are captured rather than bypass canopy patches, and are depleted as moving down rills and the associated developing ephemeral channel network. More generally, our findings indicate a potentially important but poorly documented coupling between ecohydrological and biogeochemical processes in eroding semiarid landscapes.
